Definition of: achromatic

(ak′rə·mat′ik) adjective
1. Optics Free from color or iridescence; transmitting light without showing or separating it into its constituent colors, as a lens.
2. Biol. Resisting the usual staining agents; also, containing achromatin.
3. Music Unmodulated; without accidentals. [<Gk. achrō matos <a- without + chrōma color]
—ach′ro·mat′i·cal·ly adverb
—a·chro·ma·tism (ə·krō′mə·tiz′ əm), a·chro·ma·tic·i·ty (əkrō′mə·tis′ə·tē) noun